what are soils composed of?

• 45% mineral matter

  25% air and gases

  25% water

  5% organic matter
• sand particles are large and gritty
• clay particles are tiny and smooth
• Silt particles are somewhere between clay and sand particles
• Physical and chemical weathering causes the breakdown of rocks to produce mineral matter
• The amount of air available in a soil is called soil aeration
• A soil aquires water through infiltration and percolation
• A soil aquires air though the pours in the soil
• A soil aquires organic matter through microorganisms
• What is water retention?

  the ability of a soil to hold water and make it available for use by vegetation
• The measure of the amount of space between partices is called porosity
• Clay soil is water logged as water is held strongly in small pore spaces
• In sandy soil, large pore spaces tend to contain air rater than water, these are free draining
• Nutrients gathers on the edges of each soil particle to be taken up by roots
• Soils can erode by water and wind.

  Large particles are eroded by moving short distances by creeping along land surfaces

  Smaller particles can be transported by suspention